1. Field of the Invention
The present invention relates to an improved synthetic grass surface that is filled with a mixture of sand and resilient particles, or resilient particles alone or in other combinations.
2. Description of Related Art
Synthetic turf surfaces have become widely known for use as playing field surfaces for athletic games such as tennis, football, soccer, baseball, field hockey and even golf. Such playing field surfaces are most frequently made of artificial turf or synthetic grasslike carpeting which simulate natural grass fields. Although the best of these artificial turf fields, such as those sold under the ASTROTURF brand by the assignee Southwest Recreational Industries, Inc., provide synthetic playing surfaces which closely simulate the appearance and physical character of natural turf, there is significant expense involved in knitting that synthetic turf and preparing and installing an appropriate cushioning and drainage system with that turf.
Therefore, in order to achieve a highly durable less expensive synthetic turf playing surface, there have been a number of attempts made to utilize top dressings or fillings for synthetic turf.
One problem with such filled turfs has been the tendency of the filling, usually sand, to compact over time. Thus, these surfaces have not always proved satisfactory for contact sports because the compaction of the top dressing limits the shock absorbing ability of the surface and because sand top dressing is abrasive. In an effort to remedy this problem, U.S. Pat. Nos. 4,337,283; 4,396,653; and 5,041,320 all propose introducing some shock absorbing or resilient particles.
Initial effects by the assignee to develop an economical grass-like all weather surface resulted in turf without sufficient stability, with greater than desirable abrasiveness and without adequate retention capabilities for the resilient particles.
Thus, there remains a need for a highly durable, less expensive synthetic playing surface which provides the appropriate degree and type of resiliency and does not compact over time.